Real farm management depending on the available volume of irrigation water (part II): Analysis of crop parameters and harvest quality

Abstract

The aim of MOPECO model is to maximize the gross margin of irrigated farms by a more efficient use of both the irrigable land and the irrigation water. One limitation of this model is its inability to simulate the effect of deficit irrigation on the quality of the harvests, which may affect the price perceived by the farmers. During the experiment, a farm located in Albacete (Spain) was managed by two different strategies during years 2014 and 2015. In the first strategy, the distribution of crops composed of barley, maize and onion was managed applying full irrigation (F). In the second strategy, crops were irrigated applying full irrigation or the optimized regulated deficit irrigation (O) methodology developed for MOPECO, depending on the available volume of irrigation water. The deficit levels determined by the model for reaching the maximum profitability were 0.7 of maximum evapotranspiration (ETm) for barley, and 0.9 ETm for maize and onion. The aim was to analyze the effect of the O methodology on the water productivity of the crops, on the quality of the harvests, and to determine if the O treatments would be economically penalized with regards to the F treatments due to quality drops. Hence, the O treatments reached a higher water productivity in terms of total dry biomass (average increase: 0.68kgm−3 for barley, 0.15kgm−3 for maize, and 0.01kgm−3 for onion) and dry yield (average increase: 0.26kgm−3 for barley, 0.08kgm−3 for maize, and 0.03kgm−3 for onion). The quality of the harvests and the significant differences found in this study (weight of barley and maize grains, and calibres size of bulbs in onion) did not affect the price perceived by the farmer. Due to this, the O strategy reached a higher profitability than F in the scenarios with lower availability of irrigation water (≤5000m3ha−1) (Part I). Therefore, the use of MOPECO at great scale may increase the profitability of farms located in water scarcity areas through a more efficient use of land and irrigation water.